A hydrocarbon resin is a representative tackifier and is mainly used as a material that imparts tackiness or adhesiveness to adhesive tape or products such as paint, ink, rubber, tires, etc. It is a thermoplastic resin in a liquid or solid phase at room temperature and may be provided in various forms ranging from a transparent semi-fluid liquid to a light yellow or water white solid.
A hydrocarbon resin, especially a hydrogenated hydrocarbon resin, is a thermoplastic resin prepared from a high-grade unsaturated hydrocarbon contained in thermal pyrolysis oil such as naphtha or the like in petrochemical plants, and has excellent resistance to heat and ultraviolet (UV) rays and may be adhesive, and thus may be variously utilized in medical supplies, woodworking articles and sanitary articles.
Although the number of products using hydrocarbon resin is increasing every year, the production of C5 and C9 oil fractions, currently useful as the main materials for hydrocarbon resin, is decreasing, and the shortage of material for hydrocarbon resin may become severe.
Meanwhile, in the case of a hydrogenated hydrocarbon resin, it is difficult to completely remove unreacted materials, a solvent and a low-molecular-weight oligomer during the preparation thereof, and thus, upon the manufacture of sanitary products such as diapers and the like, which involves spraying an adhesive at a high temperature, the odor of the hydrocarbon resin itself is generated, and may be released when the final product thereof is unpacked. Furthermore, the hydrogenated hydrocarbon resin may generate an offensive odor peculiar thereto when melted at a high temperature, thus adversely affecting working environments. Moreover, when it is applied to sanitary products, limitations are imposed on satisfying the needs of consumers who require the use thereof on sensitive skin, owing to odor-inducing factors.
Accordingly, since the requirement to control the odor of the hydrocarbon resin used for sanitary products is increasing with an increase in the standard of living of consumers, there is an urgent need to develop techniques for reducing the odor of the hydrocarbon resin.
In this regard, U.S. Pat. No. 5,652,308 discloses a tackifier resin in which a C3 monomer, propylene, and dicyclopentadiene (DCPD) obtained from a C5 monomer, are copolymerized using a metallocene catalyst, whereby a portion of the C5 monomer is substituted with the C3 monomer. However, when a hydrocarbon resin is prepared using the above method, an expensive metallocene catalyst, which is very vulnerable to oxygen and water, has to be used, thus causing problems of complicated process designs, high manufacturing costs and a very low yield of less than 30%, making it difficult to achieve real-world application thereof.
Also, the use of a C3 oil fraction, which is in a gas phase, requires an additional process and apparatus for the liquefaction thereof, and additional investment costs related to high-pressure reactors may be incurred, and real-world application thereof becomes difficult unless the high-pressure reactor is provided.
Moreover, Korean Patent Application No. 2013-0111233 discloses a method of preparing a hydrocarbon resin using propylene (C3 oil fraction) as an olefin, but problems such as low yield and strong odor may still occur.